Buggy code:
@ Path ( "//store" ) @ Api ( value = "//store" , tags = "store" ) @ Produces ( { "application//json" , "application//xml" } ) public class PetStoreResource { static StoreData storeData = new StoreData ( ) ; static PetData petData = new PetData ( ) ; static JavaRestResourceUtil ru = new JavaRestResourceUtil ( ) ; @ GET @ Path ( "//inventory" ) <START_BUG> @ Produces ( { MediaType . APPLICATION_JSON , MediaType . APPLICATION_XML } ) <END_BUG> @ ApiOperation ( value = "Returns<seq2seq4repair_space>pet<seq2seq4repair_space>inventories<seq2seq4repair_space>by<seq2seq4repair_space>status" , notes = "Returns<seq2seq4repair_space>a<seq2seq4repair_space>map<seq2seq4repair_space>of<seq2seq4repair_space>status<seq2seq4repair_space>codes<seq2seq4repair_space>to<seq2seq4repair_space>quantities" , response = Integer . class , responseContainer = "map" , authorizations = @ Authorization ( value = "api_key" , type = "api_key" ) ) public Map < String , Integer > getInventory ( ) { return PetStoreResource . petData . getInventoryByStatus ( ) ; } @ GET @ Path ( "//order//{orderId}" ) @ ApiOperation ( value = "Find<seq2seq4repair_space>purchase<seq2seq4repair_space>order<seq2seq4repair_space>by<seq2seq4repair_space>ID" , notes = "For<seq2seq4repair_space>valid<seq2seq4repair_space>response<seq2seq4repair_space>try<seq2seq4repair_space>integer<seq2seq4repair_space>IDs<seq2seq4repair_space>with<seq2seq4repair_space>value<seq2seq4repair_space><=<seq2seq4repair_space>5<seq2seq4repair_space>or<seq2seq4repair_space>><seq2seq4repair_space>10.<seq2seq4repair_space>Other<seq2seq4repair_space>values<seq2seq4repair_space>will<seq2seq4repair_space>generated<seq2seq4repair_space>exceptions" , response = Order . class ) @ ApiResponses ( { @ ApiResponse ( code = 400 , message = "Invalid<seq2seq4repair_space>ID<seq2seq4repair_space>supplied" ) , @ ApiResponse ( code = 404 , message = "Order<seq2seq4repair_space>not<seq2seq4repair_space>found" ) } ) public Response getOrderById ( @ ApiParam ( value = "ID<seq2seq4repair_space>of<seq2seq4repair_space>pet<seq2seq4repair_space>that<seq2seq4repair_space>needs<seq2seq4repair_space>to<seq2seq4repair_space>be<seq2seq4repair_space>fetched" , allowableValues = "range[1,5]" , required = true ) @ PathParam ( "orderId" ) String orderId ) throws NotFoundException { } @ POST @ Path ( "//order" ) @ ApiOperation ( "Place<seq2seq4repair_space>an<seq2seq4repair_space>order<seq2seq4repair_space>for<seq2seq4repair_space>a<seq2seq4repair_space>pet" ) @ ApiResponses ( { @ ApiResponse ( code = 400 , message = "Invalid<seq2seq4repair_space>Order" ) } ) public Order placeOrder ( @ ApiParam ( value = "order<seq2seq4repair_space>placed<seq2seq4repair_space>for<seq2seq4repair_space>purchasing<seq2seq4repair_space>the<seq2seq4repair_space>pet" , required = true ) Order order ) { } @ DELETE @ Path ( "//order//{orderId}" ) @ ApiOperation ( value = "Delete<seq2seq4repair_space>purchase<seq2seq4repair_space>order<seq2seq4repair_space>by<seq2seq4repair_space>ID" , notes = "For<seq2seq4repair_space>valid<seq2seq4repair_space>response<seq2seq4repair_space>try<seq2seq4repair_space>integer<seq2seq4repair_space>IDs<seq2seq4repair_space>with<seq2seq4repair_space>value<seq2seq4repair_space><<seq2seq4repair_space>1000.<seq2seq4repair_space>Anything<seq2seq4repair_space>above<seq2seq4repair_space>1000<seq2seq4repair_space>or<seq2seq4repair_space>nonintegers<seq2seq4repair_space>will<seq2seq4repair_space>generate<seq2seq4repair_space>API<seq2seq4repair_space>errors" ) @ ApiResponses ( { @ ApiResponse ( code = 400 , message = "Invalid<seq2seq4repair_space>ID<seq2seq4repair_space>supplied" ) , @ ApiResponse ( code = 404 , message = "Order<seq2seq4repair_space>not<seq2seq4repair_space>found" ) } ) public Response deleteOrder ( @ ApiParam ( value = "ID<seq2seq4repair_space>of<seq2seq4repair_space>the<seq2seq4repair_space>order<seq2seq4repair_space>that<seq2seq4repair_space>needs<seq2seq4repair_space>to<seq2seq4repair_space>be<seq2seq4repair_space>deleted" , allowableValues = "range[1,infinity]" , required = true ) @ PathParam ( "orderId" ) String orderId ) { } }

Fix:
@ Produces ( { MediaType . APPLICATION_JSON } )